Exhaust fan



FIG. 1 is a front, right and top perspective view of an exhaust fan, showing my new design;

FIG. 2 is a rear, left and bottom perspective view thereof;

FIG. 3 is a rear and bottom perspective view thereof;

FIG. 4 is a front view thereof;

FIG. 5 is a rear view thereof;

FIG. 6 is a left side view thereof;

FIG. 7 is a right side view thereof;

FIG. 8 is a top plan view thereof; and,

FIG. 9 is a bottom plan view thereof.

The broken lines shown in the drawings illustrate portions of the exhaust fan that form no part of the claimed design. 

CLAIM The ornamental design for an exhaust fan, as shown and described. 